"Yeah. One race, called Yeerks, were using people as... well, they mind control people by wrapping around the brain and keeping them prisoner in their own head. They know everything you think, see all your memories, and think people are a pretty good species to use as a ride. We can see colors and taste things -- Yeerks can't. They're like fat, overgrown slugs."

She doesn't sound too pleased as she gives him the short explanation. "The Yeerks have enslaved a few species before, and Earth was next on their list. Another alien species, called the Andalites, didn't really want that to happen -- for power struggle reasons."

She shrugs. It'd be nice to say there was altruism there, but she knows there wasn't.